The present invention relates to work positioning jigs to be attached to work fixing members of machine tools using recesses formed in the work holding surface of the fixing member.
Conventionally work is fastened to the work holding surface of a table (work fixing member) of a machine tool, for example, by an arrangement as shown in FIG. 5. With reference to FIG. 5, the work holding surface 1a of a table 1 is formed with a plurality of parallel T-slots 2 (recessed portions) each left open at lengthwise opposite ends thereof. A plurality of work positioning jigs 3 are attached to the table 1 using some of the T-slots 2. The position of the work W is determined by the jigs 3 with respect to an X-direction (see the arrow X) and a Y-direction (see the arrow Y). A plurality of clamps 4 are also attached to the table 1 using some T-slots 2. The work W is fixed to the table 1 by the clamps 4.
FIG. 6 shows the work positioning jig 3 heretofore used as attached to the table 1 with use of the T-slot 2. The jig 3 comprises a jig body 5 having a positioning portion 5a in the form of a bottomed cylinder and a fitting portion 5b formed at the lower end of the positioning portion 5a integrally therewith and fittable in a narrow portion 2a of the T-slot 2, T-slot nut 6 fittable in the T-slot 2, and a bolt 7 extending through the positioning portion 5a and the fitting portion 5b of the jig body 5 from above and screwed in the nut 6.
However, to attach the work positioning jig 3 to the table 1, it is necessary to insert the nut 6 into the T-slot 2 through the opening at lengthwise one end thereof and to tighten up the bolt 7 as by a wrench. The jig 3 therefore has the problem of necessitating a cumbersome procedure. The jig 3 also has the problem of being cumbersome to remove from the table 1 because it is necessary for removal to loosen the bolt 7 as by the wrench and to take out the nut 6 from the lengthwise end opening of the T-slot 2. Further depending on the type of the work W to be handled, it becomes necessary to use another work positioning jig 3A (indicated in chain lines in FIG. 5) after such jigs 3 and clamps 4 have been attached to the table 1. In this case, there arises a need to remove the jig 3 already attached, thereafter install the additional jig 3A and attach the removed jig 3 again. Every time the jig 3 is thus removed or attached, the T-slot nut 6 needs to be inserted into or removed from the T-slot 2 through the lengthwise end opening, and the bolt 7 must be loosened or tightened up, so that the procedure required becomes cumbersome all the more. Moreover, when the bolt 7 of the additional jig 3A or of the jig 3 temporarily removed is to be tightened up as by the wrench, the jig 3 or 3A or the clamp 4 previously installed is likely to become an obstacle, hence the problem of low work efficiency. Work W of particular type may require use of an additional jig 3A after attaching jigs 3 and clamps 4 to the table 1 and temporarily holding the work W to the table 1. In this case, the jig 3 or clamp 4 previously attached or the work W will interfere with the wrench or the like for use in tightening up the bolt 7 of the additional jig 3A to entail the problem of an impaired work efficiency.
Alternatively, the table 1 of the machine tool has a work holding surface 1a, to which work W is fastened in the manner shown in FIG. 7. Incidentally throughout FIGS. 5 to 8, like parts are designated by like reference numerals and will not be described repeatedly. With reference to FIG. 7, the work holding surface 1a of the table 1 is formed with a plurality of cylindrical bores 10 (recessed portions), and a plurality of work positioning jigs 11 are attached to the table 1 using some of the cylindrical bores 10. The position of the work W is determined by the jigs 11 with respect to an X-direction (see the arrow X) and a Y-direction (see the arrow Y).
FIG. 8 shows the work positioning jig 11 to be attached to the table 1 using the cylindrical bore 10. The jig 11 comprises a jig body 12 in the form of a cylinder having a bottom wall 12a, and a bolt 13 inserted through the bottom wall 12a from above and screwed in an internally threaded bush 14 which is fixed in the cylindrical bore 10 by a press fit.
However, the jig 11 has the problem of being cumbersome to attach to the table 1 since the bush 14 needs to be fixed into the cylindrical bore 10 by a press fit. The bolt 13 must be tightened up as by a wrench, hence the problem of necessitating a cumbersome procedure. Further depending on the type of the work W to be handled, it becomes necessary to use another work positioning jig 11A (indicated in chain lines in FIG. 7) after such jigs 11 and clamps 4 have been attached to the table 1. When the bolt 13 of the additional jig 11A is to be tightened up as by the wrench, the jig 11 or the clamp 4 previously installed is likely to become an obstacle, hence the problem of low work efficiency. Work W of particular type may require use of an additional jig 11A after attaching jigs 11 and clamps 4 to the table 1 and temporarily holding the work W to the table 1. In this case, the jig 11 or clamp 4 previously attached or the work W will interfere with the wrench or the like for use in tightening up the bolt 13 of the additional jig 11A to entail the problem of an impaired work efficiency.